From 9802724baae302a0eecbfd13839e97ca0a8c8b8f Mon Sep 17 00:00:00 2001
From: Greyson Parrelli <greyson@signal.org>
Date: Wed, 9 Feb 2022 16:08:21 -0500
Subject: [PATCH] Don't shorten message footers for mixed-direction text.

---
 .../conversation/ConversationItem.java        |  1 +
 .../securesms/util/StringUtil.java            | 26 ++++++++++
 .../StringUtilTest_hasMixedTextDirection.java | 49 +++++++++++++++++++
 3 files changed, 76 insertions(+)
 create mode 100644 app/src/test/java/org/thoughtcrime/securesms/util/StringUtilTest_hasMixedTextDirection.java

diff --git a/app/src/main/java/org/thoughtcrime/securesms/conversation/ConversationItem.java b/app/src/main/java/org/thoughtcrime/securesms/conversation/ConversationItem.java
index bdf8552b00..5cbb70504b 100644
--- a/app/src/main/java/org/thoughtcrime/securesms/conversation/ConversationItem.java
+++ b/app/src/main/java/org/thoughtcrime/securesms/conversation/ConversationItem.java
@@ -457,6 +457,7 @@ public final class ConversationItem extends RelativeLayout implements BindableCo
         isFooterVisible(messageRecord, nextMessageRecord, groupThread) &&
         !bodyText.isJumbomoji()                                        &&
         conversationMessage.getBottomButton() == null                  &&
+        !StringUtil.hasMixedTextDirection(bodyText.getText())          &&
         bodyText.getLastLineWidth() > 0)
     {
       TextView dateView           = footer.getDateView();
diff --git a/app/src/main/java/org/thoughtcrime/securesms/util/StringUtil.java b/app/src/main/java/org/thoughtcrime/securesms/util/StringUtil.java
index 4e244d5d46..bb52699cda 100644
--- a/app/src/main/java/org/thoughtcrime/securesms/util/StringUtil.java
+++ b/app/src/main/java/org/thoughtcrime/securesms/util/StringUtil.java
@@ -168,6 +168,32 @@ public final class StringUtil {
     return new String(Character.toChars(codePoint));
   }
 
+  /**
+   * @return True if the provided text contains a mix of LTR and RTL characters, otherwise false.
+   */
+  public static boolean hasMixedTextDirection(@Nullable CharSequence text) {
+    if (text == null) {
+      return false;
+    }
+
+    Boolean isLtr = null;
+
+    for (int i = 0, len = Character.codePointCount(text, 0, text.length()); i < len; i++) {
+      int  codePoint = Character.codePointAt(text, i);
+      byte direction = Character.getDirectionality(codePoint);
+
+      if (isLtr != null && isLtr && direction != Character.DIRECTIONALITY_LEFT_TO_RIGHT) {
+        return true;
+      } else if (isLtr != null && !isLtr && direction != Character.DIRECTIONALITY_RIGHT_TO_LEFT) {
+        return true;
+      } else {
+        isLtr = direction == Character.DIRECTIONALITY_LEFT_TO_RIGHT;
+      }
+    }
+
+    return false;
+  }
+
   /**
    * Isolates bi-directional text from influencing surrounding text. You should use this whenever
    * you're injecting user-generated text into a larger string.
diff --git a/app/src/test/java/org/thoughtcrime/securesms/util/StringUtilTest_hasMixedTextDirection.java b/app/src/test/java/org/thoughtcrime/securesms/util/StringUtilTest_hasMixedTextDirection.java
new file mode 100644
index 0000000000..7701480675
--- /dev/null
+++ b/app/src/test/java/org/thoughtcrime/securesms/util/StringUtilTest_hasMixedTextDirection.java
@@ -0,0 +1,49 @@
+package org.thoughtcrime.securesms.util;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+
+import java.util.Arrays;
+import java.util.Collection;
+
+import static org.junit.Assert.assertEquals;
+
+@RunWith(Parameterized.class)
+public final class StringUtilTest_hasMixedTextDirection {
+
+  private final CharSequence input;
+  private final boolean      expected;
+
+  @Parameterized.Parameters
+  public static Collection<Object[]> data() {
+    return Arrays.asList(new Object[][]{
+      { "",        false },
+      { null,      false },
+      { "A",       false},
+      { "ة",       false},  // Arabic
+      { "ی",       false},  // Kurdish
+      { "ی",       false }, // Farsi
+      { "و",       false }, // Urdu
+      { "ת",       false }, // Hebrew
+      { "ש",       false }, // Yiddish
+      { "Aة",       true }, // Arabic-ASCII
+      { "یA",       true }, // Kurdish-ASCII
+      { "Aی",       true }, // Farsi-ASCII
+      { "وA",       true }, // Urdu-ASCII
+      { "Aת",       true }, // Hebrew-ASCII
+      { "שA",       true }, // Yiddish-ASCII
+    });
+  }
+
+  public StringUtilTest_hasMixedTextDirection(CharSequence input, boolean expected) {
+    this.input    = input;
+    this.expected = expected;
+  }
+
+  @Test
+  public void trim() {
+    boolean output = StringUtil.hasMixedTextDirection(input);
+    assertEquals(expected, output);
+  }
+}